1) Field of the Invention
Embodiments of the present invention relate in general to sensor wraps for securing a sensor to a measurement site, and relate in particular to sensor wraps including foldable applicators for securing elements of the sensor within the wrap.
2) Description of the Related Art
Early detection of low blood oxygen is critical in a wide variety of medical applications. For example, when a patient receives an insufficient supply of oxygen in critical care and surgical applications, brain damage and death can result in just a matter of minutes. Because of this danger, the medical industry developed oximetry, a study and measurement of the oxygen status of blood. One particular type of oximetry, pulse oximetry, is a widely accepted noninvasive procedure for measuring the oxygen saturation level of arterial blood, an indicator of the oxygen status of the blood. A pulse oximeter relies on a sensor attached to a patient in order to measure the blood oxygen saturation.
Conventionally, a pulse oximeter sensor has a red emitter, an infrared emitter, and a photodiode detector. The sensor is typically attached to a patient""s finger, earlobe, or foot. For a finger, the sensor is configured so that the emitters project light through the outer tissue of the finger and into the blood vessels and capillaries contained inside. The photodiode is positioned at the opposite side of the finger to detect the emitted light as it emerges from the outer tissues of the finger. The photodiode generates a signal based on the emitted light and relays that signal to an oximeter. The oximeter determines blood oxygen saturation by computing the differential absorption by the arterial blood of the two wavelengths (red and infrared) emitted by the sensor.
Conventional sensors are either disposable or reusable. A disposable sensor is typically attached to the patient with an adhesive wrap, providing a secure contact between the patient""s skin and the sensor components. A reusable sensor is typically a clip that is easily attached and removed, or reusable circuitry that employs a disposable attachment mechanism, such as an adhesive tape or bandage.
The disposable sensor has the advantage of superior performance due to conformance of the sensor to the skin and the rejection of ambient light. However, repeated removal and reattachment of the adhesive tape results in deterioration of the adhesive properties and tearing of the tape. Further, the tape eventually becomes soiled and is a potential source of cross-patient contamination. The disposable sensor must then be thrown away, wasting the long-lived emitters, photodiode and related circuitry.
On the other hand, the clip-type reusable sensor has the advantage of superior cost savings in that the reusable pulse sensor does not waste the long-lived and expensive sensor circuitry. However, as mentioned above, the clip-type reusable sensor does not conform as easily to differing patient skin shape, resulting in diminished sensitivity and increased ambient light.
Similar to the clip-type reusable sensor, the circuit-type reusable sensor advantageously does not waste the sensor circuitry. On the other hand, the circuit-type reusable sensor fails to provide quality control over the attachment mechanism. Much like the disposable sensors, the attachment mechanism for the circuit-type reusable sensor may become soiled or damaged, thereby leading to cross-patient contamination or improper attachment. Moreover, because the reusable circuit is severable from the attachment mechanism, operators are free to use attachment mechanisms that are either unsafe or improper with regard to a particular type of reusable circuitry.
Based on the foregoing, significant and costly drawbacks exist in conventional disposable and reusable oximetry sensors. Thus, a need exists for an oximetry sensor that incorporates the advantages found in the disposable and reusable sensors, without the respective disadvantages.
Accordingly, one aspect of the present invention is to provide a reusable/disposable (resposable) sensor including a disposable adhesive tape component that can be removed from other reusable sensor components. This hybrid sensor combines the longevity and associated cost advantages of the reusable sensor with the performance features of the disposable.
According to one embodiment, the disposable adhesive tape comprises a sensor wrap configured to properly position the reusable sensor components with respect to each other and a measurement site. According to one embodiment, the sensor wrap includes a foldable applicator for straightforwardly attaching the reusable sensor components to the sensor wrap.
In one embodiment of the resposable sensor, the disposable tape, or sensor wrap, includes an information element along with a mechanism for the electrical connection of the information element to the emitters. The information element provides an indication to an attached oximeter of various aspects of the sensor.
According to another embodiment, the information element provides an indication of the sensor type. According to yet another embodiment, the information element provides an indication of the operating characteristics of the sensor. In yet another embodiment, the information element provides security and quality control. For instance, the information element advantageously indicates that the sensor is from an authorized supplier.
According to yet another embodiment, the information element is advantageously located in the disposable portion and configured to be in communication with the reusable portion via a breakable conductor. The breakable conductor is also located within the disposable portion such that excessive wear of the disposable portion results in isolation of the information element, thereby indicating that the disposable portion should be replaced. Moreover, the information element may comprise one or more passive or active components, ranging from a single coding resistor to an active circuit, such as a transistor network, a memory device, or a central processing component.
Therefore, aspects of one embodiment of the sensor wrap include a sensor wrap for removably securing an emitter and a detector of a pulse oximetry sensor to a measurement site. The sensor wrap also comprises a center portion configured to position an emitter and a detector of a sensor and an elongated portion extending from the center portion and configured to removably secure the sensor wrap to a measurement site. Moreover, the wrap includes a foldable portion extending from the center portion and configured to fold over the emitter and the detector when the emitter and the detector are positioned within the center portion and before application of the sensor wrap to the measurement site, thereby removably securing the emitter and detector within the center portion.
Aspects of another embodiment of the sensor wrap include a sensor wrap including a foldable tape for positioning elements of a sensor within the sensor wrap before application of the sensor wrap to a measurement site, thereby properly positioning the elements of a sensor with respect to one another, and eventually with respect to the measurement site. The sensor wrap also comprises a base tape comprising a positioning portion which receives at least one element of a sensor. The wrap also comprises a foldable tape attached to the base tape, wherein the foldable tape folds over the at least one element of the sensor before application of the sensor wrap to a measurement site, thereby removably securing the at least one element within the sensor wrap, and a fastener which removably secures the sensor wrap to the measurement site.
Aspects of another embodiment include a method of manufacturing the sensor wrap. The method comprises forming a base tape including at least one positioning element configured to position sensor elements on the base tape and forming a foldable tape including adhesive on at least one side and configured to fold over the sensor elements positioned on the base tape before application of the sensor wrap to a measurement site, thereby removably securing the sensor elements within the sensor wrap. The method also comprises connecting the foldable tape to the base tape and attaching release liners to exposed adhesive.
Aspects of another embodiment of using the sensor wrap include a method of attaching a sensor having reusable and disposable portions. The method comprises removing a release liner on a center portion of a disposable positioning tape, attaching reusable elements of a sensor to the center portion by aligning positioning elements of the sensor with positioning elements within the center portion. The method also comprises folding a foldable portion over the reusable elements of the sensor before application of the disposable positioning tape to a measurement site, thereby securing the reusable elements of the sensor within the center portion. In addition, the method comprises removing release liners from other portions of the disposable positioning tape, and affixing the disposable positioning tape, with the reusable sensor elements, to a measurement site.